Cylindrical Optical Ferrule Alignment Apparatus

ABSTRACT

An alignment sleeve for an optical fiber adapter includes features to bring precision alignment between optical fiber cores. The sleeve includes a tubular inner area to accept first and second ferrule ends of first and second connectors. First and second tabs project from first and second ends of the sleeve. The first and second tabs slide into holes in the ferrule holders or barrels of the first and second connectors, so as to provide rotational alignment of the first and second ferrules, which may be presenting multi-core optical fibers. A mid-portion of the sleeve may include geometrical features to enable a snap fit of the sleeve into a housing of the adapter. More than one tab may be employed at the ends of the sleeve, and the tabs may have defined spacing and/or dimensions to enable security keying, only permitting coupling between connectors possessing matching holes in the ferrule barrels.

This application is a continuation of application Ser. No. 14/161,792,filed Jan. 23, 2014, which claims the benefit of U.S. ProvisionalApplication No. 61/755,721, filed Jan. 23, 2013, with the entirecontents of the two prior applications being herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an adapter for communicating a firstfiber optic connector to a second fiber optic connector. Moreparticularly, the present invention relates to an alignment feature ofan adapter, which enables precise alignment of the cores of a multi-corefiber end of the first connector with the corresponding cores of amulti-core fiber end of the second connector.

2. Description of the Related Art

FIG. 1 shows an exploded view of a simplex connector, in the form of anLC connector 30, in accordance with the prior art. The LC connector 30comprises the following components, from left to right: plug housing 31;ferrule subassembly 32; spring 33; extender 34; and buffer boot 35. Forthe purposes of the present discussion, the adjectives “front” and“lead” refer to the plug end of a connector (i.e., the left side of FIG.1). The adjectives “rear” and “tail” refer to the boot end of aconnector (i.e., the right side of FIG. 1). Components 31-35 share acommon longitudinal axis 36.

In the assembled connector 30, the ferrule subassembly 32 with the cableend mounted thereto, “floats” along longitudinal axis 36 within anenclosure comprising plug housing 31, extender 34, and buffer boot 35.Spring 33 provides spring-loading of the ferrule subassembly 32 withinthe enclosure, such that the ferrule subassembly 32 is biased toward thefront end of plug housing 31. Boot 35 relieves mechanical strain on theoptical fiber cable 44.

Ferrule subassembly 32 includes a ferrule 40, a ferrule holder 41(sometimes referred to as a ferrule barrel), and tubing 42. The ferrule40 has a precision hole extending down its length, along axis 36. Thehole is shaped to closely receive a bare optical fiber from a strippedend of an optical fiber cable 44. The bare fiber is trimmed at theferrule tip 45 and polished, resulting in an exposed fiber end face 43.Ferrule holder 41 includes a hexagonal flange 46 and a front coneportion 49 having a pair of slots 47, 47′ in its perimeter. The detailsof the slots 47, 47′ and exposed fiber end face 43 are best seen in theclose-up perspective view of the ferrule subassembly 32 shown in FIG. 2.

When connector 30 is fully assembled, the ferrule tip 45 is accessiblethrough an opening 21 at the front of the plug housing 31. The plughousing 31 includes a latch arm 22 that is used to releasably attach theconnector 30 into a corresponding socket or jack (not shown).

As best seen in FIG. 3, when connector 30 is fully assembled, thehexagonal flange 46 is seated in a corresponding hexagonal cavity 23within plug housing 31, thereby limiting rotation of the flange/ferruleassembly 32 around axis 36.

FIG. 4 shows a perspective view of a tuning wrench 50 that can be usedto rotate the ferrule subassembly 32 around its longitudinal axis 36 inan assembled connector 30. The ferrule subassembly 32 can be rotated inorder to improve core alignment, as will be discussed in relation toFIG. 5. As shown in FIG. 4, the tuning wrench 50 includes a hollow shaft51 having an opening 52 therein that fits through the plug housingopening 21 and around the ferrule 40. Teeth 53, 53′ engage the pair ofslots 47, 47′ in the front cone portion 49 of the ferrule holder 41.

In use, the tuning wrench 50 pushes the ferrule subassembly 32 along itslongitudinal axis 36 toward the tail end of the assembled connector 30,such that spring 33 is compressed, and such that hexagonal flange 46 isunseated from its receiving cavity 23 in plug housing 31. Once thehexagonal flange 46 is unseated, the ferrule subassembly 32 can then befreely rotated clockwise or counter-clockwise around its longitudinalaxis 36. Releasing the tuning wrench 50 causes the hexagonal flange 46to be reseated in its receiving cavity 23. It will be appreciated thatthe ferrule subassembly 32 can only be rotated to one of sixorientations (i.e., sixty degree positional tuning) relative to the plughousing 31, corresponding to the six possible engagement locations ofthe hexagonal flange 46 within the corresponding hexagonal cavity 23 ofthe plug housing 31.

FIG. 5 illustrates the six potential placements 43A-43F of the exposedfiber end face 43. The reason the exposed fiber end face is not alwaysdead center is due to manufacturing tolerances in getting the fiber core12 centered in the cladding layer 14, and/or an off-center or cantedhole extending down the length of the ferrule 40, and/or the hole in theferrule 40 is oversized to allow for the epoxy adhering the opticalfiber into the hole, and the epoxy is not forming an even layer aroundthe optical fiber within the hole.

Therefore, it is commonly known to view and/or detect the end face 43 ofthe optical fiber and use the turning wrench 50 to select the oneposition, shown in bold with reference numeral 43E, out of the sixpotential positions 43A-43F, which best places the fiber core 12 of theexposed fiber end face 43 in the center of the opening 21 of the plughousing 31. Alternatively the fiber core can be positioned closest to apreferred location, for example 12 o'clock, to maximize transmissionbetween two coupled connectors. The best positioning of the end face 43,e.g., the position which best minimizes the eccentric error, may also bedetermined with resort to a light measuring detector, which measures theintensity of light being received from the center of the connector end.More details concerning the correction of the eccentric error can befound in US Published Application 2002/0085815, which is hereinincorporated by reference.

As can be seen in FIG. 3, the fit between the hexagonal flange 46 andthe corresponding hexagonal cavity 23 of the plug housing 31 hassignificant play 60, 61. A typical hexagon flange 46 has a widthdimension of X, e.g., 2.8000 mm, while a typical hexagonal cavity 23within the plug housing 31 has a width dimension Y, e.g., 3.0700 mm.Based upon these measurements, Applicants have evaluated the play andfound that the hexagonal flange 46 may rotated up to +/− twelve degreeswithin the hexagonal cavity 23 of the plug housing 31. The +/− play isrepresented by the double headed arrows 60 and 61 in FIG. 3. Such playhas been acceptable in the art, wherein the optic fiber 43 presented asingle core 12 transmitting light. As one could typically select one ofthe potential six positions, e.g., a sixty degree optimization, andminimize the eccentric error to a level producing acceptable dB lossacross a mated pair of connectors, and the +/− additional twelve degreesof play did not greatly deteriorate the dB loss across the mated pair ofconnectors.

A current development in the fiber arts is the multi-core optical fiber43′. As shown in FIG. 6, the multi-core optical fiber 43′ presentsmultiple cores 12 a-12 g within a single cladding layer 14. Thedepiction of FIG. 6 shows a center core 12 a and six satellite cores 12b-12 g.

When a first multi-core optical fiber connector 30 mates with a secondmulti-core optical fiber connector 30A, it is important that each core12 a-12 g of the first connector 30 comes into alignment with each core12 a-12 g of the second connector 30A. Therefore, the play 60 and 61depicted in FIG. 3 is not acceptable. A plus or minus twelve degreeshift could allow the satellite cores 12 b-12 g to be completely offsetand out of communication when a first multi-core optical fiber connector30 is mated to a second multi-core optical fiber connector 30A via apass through adapter.

To address this concern, the prior art of US Published Application2011/0229085, which is herein incorporated by reference, has reduced theallowable tolerances between the hexagonal flange 46 of the ferruleholder 41 and the hexagonal cavity 23 of the plug housing 31. In USPublished Application 2011/0229085,“a tightly toleranced internalhexagonal cavity” is employed, as it is important that the shapegeometry employed on the collar of the ferrule holder “match” the shapegeometry employed in the internal plug housing. Excessive play, e.g.,+/− twelve degrees, would not be acceptable.

In US Published Application 2011/0229085, the external geometry of theferrule holder, e.g., the hexagonal flange 46, is tightly seated withoutplay into the internal geometry of the plug housing, e.g., the hexagonalcavity 23, relatively rotatable parts of the connector which couldaffect the angular placement of the satellite cores 12 b-12 g arepreferably locked down in place with epoxy.

SUMMARY OF THE INVENTION

The Applicant has appreciated drawbacks in the multi-core fiber opticconnectors of the prior art. It is an object of the present invention toaddress one or more of the drawbacks and other perceived needs in theart.

It is appreciated that precision molding of the internal cavity of theplug housing is difficult and increases the costs. Plug housings without of tolerance internal cavities would need to be recycled. Further,the plastic portions of the housing can be subject to abrasion and mayover time expand to develop play in the nesting between the externalgeometry of the ferrule holder and the internal geometry of the plughousing, which could lead to degraded communication performance in oneor more cores. Also, the entire plug housing may slightly rotate aboutits central axis within a port of an adapter because of a clearance fitbetween the plug's housing and the walls of the port.

It is an object of the present invention to provide a low costdependable fiber optic adapter, suitable for multi-core optical fibers.

It is an object of the present invention to provide an alignment sleevewhich is robust and does not require a boss within the adapter housing,which may be snap attached into an adapter housing, and/or which maypotentially obviate the need for a two piece adapter housing.

It is an object of the present invention to provide an alignment sleevewith security keying which may prevent an unauthorized fiber connectorfrom achieving communication mating within an adapter.

These and other objects are accomplished by a device including a ferrulealignment sleeve, wherein said sleeve extends in a longitudinaldirection and forms a generally tubular inner area; a first rim formedaround a first opening at one end of said tubular area to receive an endof a first circular ferrule; a second rim formed around a second openingat an opposite end of said tubular area to receive an end of a secondferrule; and a first tab adjacent said first rim and projecting awayfrom said tubular area.

Further, these and other objects are accomplished by a device includingan adapter housing having a wall; a through hole formed in said wall ofsaid adapter housing; and a latch projecting from said wall toward saidthrough hole, wherein an end edge of said latch forms an edge of saidthrough hole, and wherein said latch is deflectable so as to deflectwithout breakage when engaged by an object larger in size than saidthrough hole being pressed into said through hole, and wherein saidlatch is resilient so as to snap back to an original position after theoversized object disengages said end edge of said latch.

Moreover, these and other objects are accomplished by a device includinga ferrule alignment sleeve, wherein said sleeve extends in alongitudinal direction and forms a generally tubular inner area, andwherein a mid-section of said sleeve includes a recessed area extendinginto an outer surface of said sleeve toward said tubular inner area; afirst rim formed around a first opening at one end of said tubular areato receive an end of a first circular ferrule; a second rim formedaround a second opening at an opposite end of said tubular area toreceive an end of a second ferrule; a first tab adjacent said first rimand projecting away from said tubular area; a second tab adjacent saidsecond rim and projecting away from said tubular area; an adapterhousing having a wall; a through hole formed in said wall of saidadapter housing; and a latch projecting from said wall toward saidthrough hole, wherein an end edge of said latch forms an edge of saidthrough hole, and wherein said latch is deflectable so as to deflectwithout breakage when engaged by an object larger in size than saidthrough hole being pressed into said through hole, wherein said latch isresilient so as to snap back to an original position after the oversizedobject disengages said end edge of said latch, and wherein said at leastone resilient latch snaps into said recessed area of said sleeve as saidsleeve passes through said through hole and acts to attach said sleevewithin said adapter housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawings,which are given by way of illustration only, and thus, are not limits ofthe present invention.

FIG. 1 is an exploded, perspective view of an LC connector for anoptical fiber, in accordance with the prior art;

FIG. 2 is a close-up, perspective view of a ferrule subassembly in FIG.1;

FIG. 3 is a diagram depicting play in the fitting of a hexagonal flangeof a ferrule holder within a hexagonal cavity of a plug housing, inaccordance with the prior art;

FIG. 4 is a perspective view of a turning wrench, in accordance with theprior art;

FIG. 5 is a diagram depicting six potential locations of a fiber endpresented by a fiber optical connector due to an eccentric error in thefiber placement, in accordance with the prior art;

FIG. 6 is an end view of a multi-core optical fiber, in accordance withthe prior art;

FIG. 7 is a perspective view of an alignment sleeve, in accordance witha first embodiment of the present invention;

FIG. 8 is a top view of the alignment sleeve of FIG. 7;

FIG. 9 is a side view of the alignment sleeve of FIG. 7;

FIG. 10 is a perspective view of a fiber optic adapter, in accordancewith a first embodiment of the present invention;

FIG. 11 is an end view looking into the adapter in the direction of lineXI-XI of FIG. 10;

FIG. 12 is a cross-sectional view taken along line XII-XII in

FIG. 11, and also illustrating the partial insertion of a fiberconnector;

FIG. 13 is a perspective view of first and second mated fiber connectorswithin the adapter of FIG. 10, with all of the structure except thealignment sleeve removed from the adapter, and all of the structureexcept the ferrules, ferrule holders, and tubes removed from the firstand second fiber connectors;

FIG. 14 is a side view of the arrangement of FIG. 13;

FIG. 15 is a perspective view of a modified alignment sleeve withsecurity keying features;

FIG. 16 is a perspective view of an alignment sleeve, in accordance witha second embodiment of the present invention;

FIG. 17 is a top view of the alignment sleeve of FIG. 16;

FIG. 18 is a side view of the alignment sleeve of FIG. 16;

FIG. 19 is an end view looking into the ports of a fiber optic adapter,in accordance with a second embodiment of the present invention;

FIG. 20 is an end view similar to FIG. 19, but showing alignment sleevesof FIG. 16 being mounted within the ports; and

FIG. 21 is a perspective view of a cross-section taken along lineXXI-XXI in FIG. 20, with first and second fiber connectors mated intothe adapter.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, thethickness of certain lines, layers, components, elements or features maybe exaggerated for clarity. Broken lines illustrate optional features oroperations unless specified otherwise.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

As used herein, the singular forms “a”, an and the are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. As used herein, phrases such as “between X and Y” and“between about X and Y” should be interpreted to include X and Y. Asused herein, phrases such as “between about X and Y” mean “between aboutX and about Y.” As used herein, phrases such as “from about X to Y” mean“from about X to about Y.”

It will be understood that when an element is referred to as being “on”,“attached” to, “connected” to, “coupled” with, “contacting”, etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on”, “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” another feature may have portions thatoverlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper”, “lateral”, “left”, “right” and the like, may be used herein forease of description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. It willbe understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is inverted, elements described as “under” or“beneath” other elements or features would then be oriented “over” theother elements or features. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the descriptors ofrelative spatial relationships used herein interpreted accordingly.

FIGS. 7-9 show various views of a ferrule alignment sleeve 101, inaccordance with a first embodiment of the present invention. The sleeve101 extends in a longitudinal direction 102 and forms an inner,generally tubular area 103. A first rim 105 is formed around a firstopening at one end of the tubular area 103 to receive an end of a firstcircular ferrule 40 (see FIG. 12). A second rim 107 is formed around asecond opening at an opposite end of the tubular area 103 to receive anend of a second ferrule 40A.

A first tab 109 is located adjacent to the first rim 105 and projectsaway from the tubular area 103. A second tab 111 is located adjacent tothe second rim 107 and projects away from the tubular area 103. In apreferred embodiment, the first tab 109 has a generally radiused ortriangular tip at its distal end 113, and the second tab 111 also has agenerally radiused or triangular tip at its distal end 115.

In one embodiment, the sleeve 101 is split in a direction parallel toits longitudinal line of extension 102 by an opening 117. Hence, thesleeve 101 presents a C-shaped appearance in a cross-sectional view,taken through the tubular area 103 in a direction perpendicular to itslongitudinal line of extension 102. The sleeve 101 may be formed ofzirconia, alumina, phosphor bronze, stainless steel, a filled polymer orunfilled polymer, a metal, an alloy, glass, ceramic, or similarmaterial. Also, the sleeve 101 may be coated with a hard material, likediamond-grade materials or titanium nitride, to reduce wear due toabrasion. In the embodiment depicted in FIGS. 7-9, the outer surface 119of the sleeve 101 presents a generally smooth, cylindrical surface.

FIG. 10 is a perspective view of a fiber optic adapter 201, inaccordance with a first embodiment of the present invention. FIG. 11 isan end view looking into the adapter 201 in the direction of line XI-XIin FIG. 10. FIG. 12 is a cross-sectional view taken along line XII-XIIin FIG. 11, and also illustrating the partial insertion of a fiberconnector.

The depicted adapter 201 is a duplex adapter having first and secondports 250 and 250A on one lateral side, with each port 250 or 250A sizedto receive one of a mating pair of connectors, e.g., connectors 30 ofFIG. 1. Third and fourth ports 251 and 251A are located on the oppositelateral side of the adapter 201. A connector 30 in first port 250 willhave its single core or multi-core optical fiber mated to the opticalfiber of a connector 30 in the second port 250A. Likewise, a connector30 in third port 251 will have its single core or multi-core opticalfiber mated to the optical fiber of a connector 30 in the fourth port251A. Since the structure concerning the first and second ports 250,250A is the same as the structure concerning the third and fourth ports251, 251A, the following description will focus on the first and secondports 250 and 250A only.

The adapter 201 is formed by a housing including by a first part 203with a first wall 205 and a second part 207 with a second wall 209. Afirst through hole 211 is formed in the first wall 205 of the first part203. A second through hole 213 is formed in said second wall 209 of thesecond part 207.

A first cylindrical boss 215 has a proximate end attached to the firstwall 205 and encircles the first hole 211. The first cylindrical boss215 extends away from the first wall 205 and terminates at a distal endwith a first turned edge 217 protruding toward a center of the firstcylindrical boss 215. The first turned edge 217 has a first gap 219.

A second cylindrical boss 221 has a proximate end attached to the secondwall 209 and encircles the second hole 213. The second cylindrical boss221 extends away from the second wall 209 and terminates at a distal endwith a second turned edge 223 protruding toward a center of the secondcylindrical boss 221. The second turned edge 223 has a second gap 225.

The first wall 205 abuts, and is retained in abutment, with the secondwall 209 while the first and second holes 211 and 213 are aligned, asillustrated in FIG. 12. The first and second walls 205 and 209 can beretained in the abutment position by adhesion, e.g., epoxy, by a fixingdevice, e.g., a clip, by molded features, e.g., snap engagingcomponents, by ultrasonic welding, or by other known methods. Prior toattachment, the sleeve 101 of FIGS. 7-9 is inserted into the alignedholes 211 and 213. In particular, the sleeve 101 resides inside of thefirst boss 215 and the second boss 221. FIG. 11 depicts a sleeve 101installed in the first port 250, but no sleeve installed in the thirdport 251.

The first rim 105 of the sleeve 101 cannot pass by the first turned edge217 of the first boss 215 and the second rim 107 of the sleeve 101cannot pass by the second turned edge 223 of the second boss 221. Bythis arrangement, the sleeve 101 is attached within the first and secondbosses 215 and 221, and hence within the housing of the adapter 201. Thefirst tab 109 of the sleeve 101 passes through the first gap 219 in thefirst turned edge 217. The second tab 111 of the sleeve 101 passesthrough the second gap 225 in the second turned edge 223.

The first port 250 resides on a side of the first wall 205 possessingthe first boss 215. The second port 250A resides on a side of saidsecond wall 209 possessing the second boss 221. A first fiber opticconnector 30 would be seated into the first port 250. The first fiberoptic connector 30 would include a first ferrule holder 41 holding afirst ferrule 40 and a first optical fiber end 43 residing within acentral bore of the first ferrule 40. FIG. 12 depicts the firstconnector 30 being partially inserted into the first port 250. As thefirst connector 30 is fully seated into the first port 250, the firstconnector's latch arm 22 will enter into a latch track 252 and snap lockin place. As the first connector 30 begins to fully seat, the first tab109 of the sleeve 101 extends into the first slot 47 formed in the firstferrule holder 41. The generally radiused or triangular tip at thedistal end 113 of the first tab 109 assists in the insertion of thefirst tab 109 into the first slot 47.

A second fiber optic connector 30A would be seated into the second port250A. The second fiber optic connector 30A would include a secondferrule holder 41A holding a second ferrule 40A and a second opticalfiber end 43A residing within a central bore of the second ferrule 40A.As the second connector 30A is fully seated into the second port 250A,the second latch arm 22A will enter into a second latch track 252A andsnap lock in place. As the second connector 30A begins to fully seat,the second tab 111 of the sleeve 101 extends into the second slot 47Aformed in the second ferrule holder 41A. The generally radiused ortriangular tip at the distal end 115 of the second tab 111 assists inthe insertion of the second tab 111 into the second slot 47A.

FIG. 13 is a perspective view of the first and second mated fiberconnectors 30 and 30A within the adapter 201 of FIG. 10, with all of thestructure except the alignment sleeve 101 removed from the adapter 201,and all of the structure except the ferrules 40 and 40A, ferrule holders41 and 41A, and tubes 42 and 42A removed from the first and second fiberconnectors 30 and 30A. FIG. 14 is a side view of the arrangement of FIG.13.

As seen in FIGS. 13-14, when the first and second tabs 109 and 111engage into the first and second slots 47 and 47A, the first and secondslots 47 and 47A become quite precisely aligned. The alignment can bevery advantageous when the first optical fiber 43 is a first multi-coreoptical fiber, e.g., FIG. 6, and the second optical fiber 43A is asecond multi-core optical fiber. By clocking the position of thesatellite cores 12 b-12 g relative to the lower slot 47 of the ferruleholder 41 prior to attaching the fiber 43 to the ferrule 40, e.g., byepoxy, it will be known that the first and second multi-core opticalfibers 43 and 43A are aligned with each other, such that all of thecores 12 a-12 g are in communication when the first and second tabs 109and 111 of the sleeve 101 create an alignment between the lower slots 47and 47A and the ends 45 and 45A of the ferrules 40 and 40A abut.

If only the inner cavity 23 of the connector housing were used to alignthe multi-core fibers, the alignment could be off by up to plus or minustwelve degrees, as shown in FIG. 3. However, by the present invention'suse of the “existing” slot 47 in the ferrule holder 41, previously usedto rotate the ferrule to improve upon the eccentric error of a singlecore fiber, the alignment error can be reduce to plus or minus one and ahalf degrees or less. Such a small angular variation allows thesatellite cores 12 b-12 g to stay in alignment for effectivecommunication across a pass-through adapter 201.

Instead of using “existing” ferrule holders 41 with “existing” slots 47and 47′, it is within the purview of the present invention, to machine aferrule holder with a slot or plural slots design for the optimizationof the function of the present invention. To that end, the slot could bewider at its opening and narrow down to a precise size. The wideropening could assist in the initial “finding” of the slot by the tabs109 or 111, and could operate in conjunction with the radius ortriangular shape at the ends 113 and 115 of the tabs 109 and 111.Further, the previous slots 47 and 47′ were designed only to engage withthe teeth 53 and 53′ of the wrench 50 of FIG. 4, so as to permit a largecourse rotation of the ferrule holder, e.g., sixty degree. Thedimensional tolerances of the prior art slots 47 and 47′ are not ofgreat concern. In accordance with the present invention, the dimensionaltolerances can be more precise and monitored during fabrication of theferrule holder 41. A close tolerance for the slots 47 or 47′ can furtherreduce the potential plus or minus error of the rotational alignment ofthe satellite cores 12 b-12 g.

It is also a feature of the present invention that slots 47 could beclosely spaced at precise distances from each other, have different andprecise widths and or depths. The slots 47 could then be used as akeying feature. For example, FIG. 15 is a perspective view of a modifiedalignment sleeve 161 with security keying features to engage in such aferrule holder with multiple keying slots.

The sleeve 161 includes a first tab 163 located adjacent to the firstrim 105 and projecting away from the tubular area 103, and a second tab165 located adjacent to the second rim 107 and projecting away from thetubular area 103. The sleeve 161 further includes a third tab 167adjacent the first rim 105 and projecting away from the tubular area 103and a fourth tab 169 adjacent the second rim 107 and projecting awayfrom the tubular area 103. The third tab 167 is spaced a predetermineddistance away from the first tab 163. The fourth tab 169 is spaced apredetermined distance away from the second tab 165. The predeterminedspacing is a first keying aspect, such that a ferrule holder 41, whichdoes not possess two slots spaced by the predetermined distance, willnot be able to fully seat into first port 250 of the adapter 201 andwill therefore not be allowed to communicate with another connectorseated into the second port 250A of the adapter 201.

As also seen in FIG. 15, the width dimension of the third tab 167 isdifferent, e.g., narrower, than the width dimension of the first tab163, and the width dimension of the fourth tab 169 is different, e.g.,narrower, than the width dimension of the second tab 165. The widthdimensions are a second keying aspect, such that a ferrule holder 41,which does not possess two slots with the matching widths, will not beable to fully seat into the first port 250 of the adapter 201 and willtherefore not be allowed to communicate with another connector seated inthe second port 250A of the adapter 201.

As also seen in FIG. 15, the length dimension of the third tab 167 isdifferent, e.g., longer, than the length dimension of the first tab 163,and the length dimension of the fourth tab 169 is different, e.g.,longer, than the length dimension of the second tab 165. The lengthdimensions are a third keying aspect, such that a ferrule holder 41,which does not possess two slots with the correct depths, will not beable to fully seat into the first port 250 of the adapter 201 and willtherefore not be allowed to communicate with another connector seated inthe second port 250A of the adapter 201.

Such keying features may be used to enhance network security bypreventing unauthorized network access to individuals not in possessionof a fiber connector with a ferrule holder 41 having the proper keyingfeatures, e.g., slot arrangement.

FIGS. 16-18 show various views of a ferrule alignment sleeve 301, inaccordance with a second embodiment of the present invention. The sleeve301 extends in a longitudinal direction 302 and forms an inner,generally tubular area 303. A first rim 305 is formed around a firstopening at one end of the tubular area 303 to receive an end of a firstcircular ferrule 40 (see FIG. 21). A second rim 307 is formed around asecond opening at an opposite end of the tubular area 303 to receive anend of a second ferrule 40A.

A first tab 309 is located adjacent to the first rim 305 and projectsaway from the tubular area 303. A second tab 311 is located adjacent tothe second rim 307 and projects away from the tubular area 303. In apreferred embodiment, the first tab 309 has a generally radiused ortriangular tip at its distal end 313, and the second tab 311 also has agenerally radiused or triangular tip at its distal end 315.

In one embodiment, the sleeve 301 is split in a direction parallel toits longitudinal line of extension 302 by an opening 317. Hence, thesleeve 301 presents a C-shaped appearance in a cross-sectional view,taken through some portions of the tubular area 303 in a directionperpendicular to its longitudinal line of extension 302. The sleeve 301may be formed of zirconia, alumina, phosphor bronze, stainless steel, afilled polymer or unfilled polymer, a metal, an alloy, glass, ceramic,or similar material. Also, the sleeve 301 may be coated with a hardmaterial, like diamond-grade materials or titanium nitride, to reducewear due to abrasion.

In the embodiment depicted in FIGS. 16-18, the majority of the outersurface 319 of the sleeve 301 presents a generally smooth, cylindricalsurface. However, the sleeve 301 of FIGS. 16-18 is thicker and much morerobust that the sleeve 101 of FIGS. 7-9. A mid-section of the sleeve 301includes a recessed area 321 extending into the outer surface 319 of thesleeve 301 toward the tubular inner area 303. In a preferred embodiment,the recessed area 321 includes a plurality of flat surfaces, such asfirst, second, third and fourth flat surfaces 323, 325, 327 and 329.

FIGS. 19-20 are end views of a fiber optic adapter 401, in accordancewith a second embodiment of the present invention. The exterior of theadapter 401, in perspective view, is the same as depicted in FIG. 10.Also, the adapter 401 would include four ports for making opticalconnections, as described in connection with FIG. 10.

In the end view of FIG. 19, the adapter 401 has a housing including awall 405. A through hole 411 is formed in the wall 405. A first latch413 projects from the wall 405 toward the through hole 411. Likewise,second, third and fourth latches 415, 417 and 419 project from the wall405 toward different perimeter portions of the through hole 411.

In a preferred embodiment, the first resilient latch 413 is a portion ofthe wall 405 defined between a first void channel 421 and a second voidchannel 423. The second resilient latch 415 is a portion of the wall 405defined between the second void channel 423 and a third void channel425. The third resilient latch 417 is a portion of the wall 405 definedbetween the third void channel 425 and a fourth void channel 427.Finally, the fourth resilient latch 419 is a portion of the wall 405defined between the fourth void channel 427 and the first void channel421.

Also in the preferred embodiment, end edges of said latches 413, 415,417 and 419 form an edge of the through hole 411. Each latch 413, 415,417 and 419 is deflectable so as to deflect without breakage whenengaged by an object slightly larger in size than the through hole 411being pressed into the through hole 411. Also, each latch 413, 415, 417and 419 is resilient so as to snap back to an original position afterthe oversized object disengages the end edges of the latches 413, 415,417 and 419.

FIG. 20 depicts the insertion of the sleeve 301 of FIGS. 16-18 into theadapter 401. In FIG. 20, a sleeve 301 has been inserted into the throughholes 411 of both ports 450 and 451 of the adapter 401. During insertionof the sleeve 301, the latches 413, 415, 417 and 419 deflect as thelarge cylindrical outer surface 319 enters the through hole 411. Oncethe leading edge of the recessed area 321 reaches the latches 413, 415,417 and 419, the latches 413, 415, 417 and 419 snap into the recessedarea 321 of said sleeve 301.

The latches 413, 415, 417 and 419 act to attach the sleeve 301 to thewall 405 within the housing of the adapter 401. In particular, thefirst, second, third and fourth flat surfaces 323, 325, 327 and 329 areengaged by the end edges of the first, second, third and fourth latches413, 415, 417 and 419, respectively.

FIG. 21 is a perspective view of a cross-section taken along lineXXI-XXI in FIG. 20 with first and second fiber connectors 30 and 30Amated into the adapter 401.

The adapter 401 has a housing including a first port 450 on a first sideof the wall 405 and a second port 450A on a second side of the wall 405.A first fiber optic connector 30 is seated into the first port 450. Thefirst fiber optic connector 30 includes a first ferrule holder 41holding a first ferrule 40 and a first optical fiber end 43 residingwithin a central bore of the first ferrule 40

A second fiber optic connector 30A is seated into the second port 450A.The second fiber optic connector 30A includes a second ferrule holder41A holding a second ferrule 40A and a second optical fiber end 43Aresiding within a central bore of the second ferrule 40A.

The first tab 309 of the sleeve 301 extends into a first slot 47 formedin the first ferrule holder 41 when the first fiber optic connector 30is seated into the first port 450. The said second tab 311 of the sleeve301 extends into a second slot 47A formed in the second ferrule holder41A when the second fiber optic connector 30A is seated into the secondport 450A. The engagements made by the sleeve 301 align the first andsecond slots 47 and 47A of the first and second ferrule holders 41 and41A, in a same or similar manner as described in conjunction with FIGS.12-14. Again, the arrangement of FIG. 21 is particularly advantageouswhen the first optical fiber end 43 presents a first multi-core opticalfiber, and the second optical fiber end 43A presents a second multi-coreoptical fiber, as the alignment of the said first and second slots 47and 47A aligns the cores of the first and second multi-core opticalfiber ends 43 and 43A during connector mating via the adapter 401.

The embodiment of FIGS. 16-21 has advantages over the embodiment ofFIGS. 7-15. For example, the recessed area 321, e.g., squared section,prevents a twisting force from being transferred through the sleeve 301to the ferrule holder 41 or 41A of the other connector 30 or 30A. Anytwisting force applied by a ferrule holder 41 or 41A to the sleeve 301will be absorbed by the latches 413, 415, 417 and 419, rather thattransmitted through the adapter 310 to impart a twisting force on theother connector's ferrule holder.

Another advantage is that the adapter 401 need not be formed in twopieces as illustrated in FIG. 21. Rather, the wall 405 may be a sharedwall between the first and second ports 450 and 450A. In the embodimentof FIGS. 7-15, it was convenient to separate the adapter 201 into halves203 and 207, so as to insert the sleeve 101 into the bosses 215 and 221for retention. In the embodiment of FIGS. 16-21, the sleeve 301 iscombined with the function of the bosses, and snaps into place withinthe adapter 401, rendering the two piece construction unnecessary forretention of the sleeve 301.

Instead of sleeve 301 snapping into the wall 405 of the adapter 401, thesleeve 301 could also be adhered, e.g., by epoxy, or clipped or fastenedinto the adapter 401 by an attachment device, e.g., a clip, or moldeddirectly into the wall 405 of the adapter 401.

The security keying features, as described in conjunction with theembodiment of FIG. 15, may also used in the embodiments of FIGS. 16-21in a same or similar manner.

Although the figures have depicted LC type connectors with a hexagonflange 46 on the ferrule holder 41, it should be appreciated that thehexagonal shape of the flange 46 is not necessary in an LC connector 30,as the flange 46 could be square, conical, round with tabs or anycombination of geometries known to one in the art. Also, the presentinvention is not limited to LC type connectors 30. For example, simplexand duplex connector schemes using other type connectors such as SC, FC,ST, MU or 38999/29504 connector types may be substituted into theteachings of the present invention. Also, the mating of bare ferrulebarrel assemblies could be accomplished (as shown in FIGS. 13-14),whereby no connector envelope is employed.

Although the figures have depicted a split sleeve 101, 161 or 301, itshould be apparent that a solid sleeve may be used in the embodiments ofthe invention.

Although the specification has described, and FIG. 6 has illustrated, amulti-core optical fiber end 43′ with a central core 12 a and six,equally-spaced, satellite cores 12 b-12 g, more or fewer satellitescores could be used. Further, the spacing between cores need not beequal or even symmetrical. Further, a central core 12 a is not required.The benefits of the present invention in aligning a first layout patternof cores in a multi-core optical fiber end 43′ to a same layout patternof cores in another multi-core optical fiber end 43A′ will existregardless of any specific core pattern, so long as the pattern at thefirst optical fiber end 43′ is the same as the pattern at the secondoptical fiber end 43A′.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

1. A device comprising: a ferrule alignment sleeve, wherein said sleeveextends in a longitudinal direction and forms an inner, generallytubular area; a first rim formed around a first opening at one end ofsaid generally tubular area to receive an end of a first ferrule; and afirst tab adjacent said first rim and projecting away from said firstrim and said generally tubular area to interact with a featureassociated with the first ferrule to angularly align the first ferrulewithin said generally tubular area.
 2. The device of claim 1, whereinsaid sleeve is split along its longitudinal line of extension.
 3. Thedevice of claim 1, wherein an outer surface of said sleeve presents agenerally cylindrical surface.
 4. The device of claim 1, furthercomprising: a second rim formed around a second opening at an oppositeend of said generally tubular area to receive an end of a secondferrule; and a second tab adjacent said second rim and projecting awayfrom said second rim and said tubular area to interact with a featureassociated with the second ferrule to align the second ferrule withinsaid generally tubular area, and wherein said sleeve is split along itslongitudinal line of extension.
 5. The device of claim 1, wherein saidfirst tab has a generally radiused or triangular tip at its distal end.6. The device of claim 1, wherein a mid-section of said sleeve includesa recessed area extending into an outer surface of said sleeve towardsaid generally tubular inner area.
 7. The device of claim 6, furthercomprising: a housing having a wall; a through hole formed in said wallof said housing; and at least one resilient latch projecting from saidwall toward said through hole, wherein said at least one resilient latchsnaps into said recessed area of said sleeve as said sleeve passesthrough said through hole and acts to attach said sleeve within saidhousing.
 8. The device of claim 7, wherein said at least one resilientlatch includes first and second resilient latches projecting towarddifferent perimeter portions of said through hole, and wherein saidrecessed area includes first and second flat surfaces, which are engagedby said first and second resilient latches, respectively, when saidsleeve is attached within said housing.
 9. The device of claim 8,wherein said first and second resilient latches are first and secondportions of said wall defined between void channels formed in said wall.10. The device of claim 7, further comprising: a second rim formedaround a second opening at an opposite end of said generally tubulararea to receive an end of a second ferrule; a second tab adjacent saidsecond rim and projecting away from said second rim and said tubulararea to interact with a feature associated with the second ferrule toalign the second ferrule within said generally tubular area, and whereinsaid sleeve is split along its longitudinal line of extension, andwherein said housing is an adapter housing and includes a first port ona first side of said wall and a second port on a second side of saidwall; a first fiber optic connector seated into said first port, saidfirst fiber optic connector including a first ferrule holder holdingsaid first ferrule and a first optical fiber residing within a centralbore of said first ferrule; and a second fiber optic connector seatedinto said second port, said second fiber optic connector including asecond ferrule holder holding said second ferrule and a second opticalfiber residing within a central bore of said second ferrule; whereinsaid first tab of said sleeve extends into a first slot formed in saidfirst ferrule holder when said first fiber optic connector is seatedinto said first port, and said second tab of said sleeve extends into asecond slot formed in said second ferrule holder when said second fiberoptic connector is seated into said second port, so as to align saidfirst and second slots of said first and second ferrule holders.
 11. Thedevice of claim 10, wherein said first optical fiber is a firstmulti-core optical fiber, and said second optical fiber is a secondmulti-core optical fiber, and wherein when said first and second slotsof said first and second ferrule holders are aligned, cores of saidfirst and second multi-core optical fibers are aligned.
 12. A devicecomprising: a ferrule alignment sleeve, wherein said sleeve extends in alongitudinal direction and forms an inner, generally tubular area; afirst rim formed around a first opening at one end of said generallytubular area to receive an end of a first ferrule; a first tab adjacentsaid first rim and projecting away from said generally tubular area; ahousing having a first part with a first wall; a first through holeformed in said first wall of said first part; and a first cylindricalboss having a proximate end attached to said first wall and encirclingsaid first hole, said first cylindrical boss extending away from saidfirst wall and terminating at a distal end with a first turned edgeprotruding toward a center of said first cylindrical boss, with a firstgap formed in said first turned edge; wherein said sleeve resides insidesaid first boss, wherein said first rim of said sleeve cannot pass bysaid first turned edge of said first boss, so as to attach said sleevewithin said housing, and wherein said first tab of said sleeve passesthrough said first gap in said first turned edge.
 13. The device ofclaim 12, wherein said housing includes a first port on a side of saidfirst wall possessing said first boss, and further comprising: a firstfiber optic connector seated into said first port, said first fiberoptic connector including a first ferrule holder holding said firstferrule and a first optical fiber residing within a central bore of saidfirst ferrule; wherein said first tab of said sleeve extends into afirst slot formed in said first ferrule holder when said first fiberoptic connector is seated into said first port.
 14. The device of claim13, wherein said first optical fiber is a first multi-core opticalfiber.
 15. The device of claim 4, further comprising: a third tabadjacent said first rim and projecting away from said first rim and saidtubular area, wherein said third tab is spaced a predetermined distanceaway from said first tab.
 16. The device of claim 15, wherein said thirdtab has a width dimension which is different than a width dimension ofsaid first tab.
 17. A device comprising: a ferrule alignment sleeve,wherein said sleeve extends in a longitudinal direction and forms agenerally tubular inner area, and wherein a mid-section of said sleeveincludes a recessed area extending into an outer surface of said sleevetoward said tubular inner area; a first rim formed around a firstopening at one end of said tubular area to receive an end of a firstferrule; a second rim formed around a second opening at an opposite endof said tubular area; a first tab adjacent said first rim and projectingaway from said first rim and said tubular area; a housing having a wall;a through hole formed in said wall of said housing; and a latchprojecting from said wall toward said through hole, wherein an end edgeof said latch forms an edge of said through hole, and wherein said latchis deflectable so as to deflect without breakage when engaged by anobject larger in size than said through hole being pressed into saidthrough hole, wherein said latch is resilient so as to snap back to anoriginal position after the oversized object disengages said end edge ofsaid latch, and wherein said at least one resilient latch snaps intosaid recessed area of said sleeve as said sleeve passes through saidthrough hole and acts to attach said sleeve within said housing.
 18. Thedevice of claim 17, wherein said latch is a first latch, and furthercomprising: a second latch projecting from said wall toward said throughhole, wherein an end edge of said second latch forms an edge of saidthrough hole along a different perimeter portion of said through hole,and wherein said second latch is deflectable so as to deflect withoutbreakage when engaged by an object larger in size than said through holebeing pressed into said through hole, and wherein said second latch isresilient so as to snap back to an original position after the oversizedobject disengages said end edge of said second latch.
 19. The device ofclaim 18, wherein said first and second latches are first and secondportions of said wall defined between void channels formed in said wall.